Etiological Similarities Between Psychological and Physical Aggression in Intimate Relationships: A Behavioral Genetic Exploration

Previous research has consistently shown that there is a strong association between psychological and physical aggression in intimate relationships. Theories as to why this association exists include that they have a single underlying etiology with differing thresholds, or they have separate etiologies and there is a two-step process by which psychological aggression moves to physical. The current study suggests that these two theories are not necessarily competing theories. The genetic and environmental covariance between psychological and physical intimate partner aggression were examined in 134 monozygotic (MZ) and 41 dizygotic (DZ) twin pairs. Results showed that psychological and physical aggression have largely the same genetic etiology, and any differences between the two are a function of differing nonshared environmental influences.